A semi-analytical model for calculating PM eddy-current loss of YASA AFPM machine for electric propulsion

For the axial flux permanent magnet (PM) (AFPM) machine, such as the yokeless and segmented armature (YASA) AFPM machine, the eddy-current loss in the permanent magnet (PM) is usually calculated by three-dimensional (3-D) finite-element model (FEM), which is precise but time-consuming. This paper introduces a semi-analytical model designed to calculate the eddy-current loss in PMs for YASA AFPM machines, specifically for electric aircraft propulsion applications. An equivalent model is firstly established to predict the flux densities at different locations of the magnets. The precision of the calculation for PM eddy-current loss by semi-analytical model with different horizontal and vertical segments is validated. The losses are determined by the proposed model under different rotating speeds and working conditions, and then compared with the 3-D FEM results. The results show that the relative errors are less than 8%. Besides, the computation time is decreased from 1.2 hour to 5 min for each condition, which makes the semi-analytical model suitable for motor optimization.